Lots of good thoughts here - the one thing I would add is it's worth considering more than just the financial aspects of debt vs. being debt-free. While it's been alluded to there is the mental health aspect, but the part that seems to have been missed is the physical health costs from trying to do things on the cheap or manually. Sure not having that monthly payment might be low stress, but trashing your body in order to be debt free can quickly end up costing more (especially in the long run).
It's a lesson I've learned the hard way -- and seen other succumb to as well from trying to pinch pennies, or from pushing things beyond the limits in sports and/or physical labor/work. As a coworker quipped/quoted not that long ago: "At some point a person's health goals evolve into simply avoiding the need for aftermarket parts".
So being someone who had high school friends get aftermarket parts installed (prior to graduating high school), and has had doctor's identify joint problems (and some that have never been properly diagnosed) that can't be corrected .... I'd say there are some very important limits/considerations that should also be weighed against the desire to be debt free. ....and I'm saying that as someone who absolutely hates being in debt (or even owing anyone anything) as I'm also in my late 30's and have put my body through enough that I consciously chose to walk away from sports and weight training (both of which I greatly enjoyed) in order to increase the odds of being able to walk unassisted for the remainder of my life. It really wasn't fun being 18 and having to worry about whether my knees would actually support me when I stood up (thankfully in the years since I've mostly healed/recovered).
The other thing to consider is that in order to maintain a good credit rating generally requires actually using credit/debt. If I'm recalling correctly (it's been a few years) I've actually seen my credit rating go down before because I wasn't carrying "enough" debt to support the high credit rating I generally maintain (i.e. a FICO score that's routinely above 820).
Being debt free may feel great, but getting to the point where you realize you not only have a positive net worth/wealth, but are having financial institutions known to be very conservative/risk adverse routinely attempting to market/throw more money at you than you're willing to borrow is a truly AWESOME feeling (especially when you can also resist the temptation of taking the money they are offering without a second thought).
So personally, I'd say it comes down to having the wisdom to determine what is wanted vs. needed, weigh all the costs (which should include considering the costs avoided), and having the self-control/self-discipline to follow the decided upon coarse of action (and adjust if/when it becomes necessary to do so). On that note, my personal rule for acceptable debt usage has pretty much evolved to: a mortgage (traditional limits or less), plus one additional secured low/no interest loan (generally either a vehicle or required equipment), and using no more than 1/3 of a credit card's limit (with all balances being paid in full by the due date).
I may occasionally waver from that, but if I do it's to avoid other costs, or taking money from accounts that are earning more than I'll pay in interest costs -- granted that's not always the simplest thing to calculate/consider (even with a background in engineering and economics) so I don't do it often, and would imagine it's partially why Dave Ramsey pushes the debt-free concept as much as he does.
The other thing I've come to realize is that gaining/maintaining such self-control/self-discipline can also make so many other aspects of life so much easier and more enjoyable -- which in turn helps me focus my life on the things that actually matter.
On that note, best of wishes to everyone ...and as always the applicability of the above may vary depending on your personal situation.
